The objective of the program is to gain increased understanding of the neural mechanisms which underlie hearing through an integrated series of studies: 1) determination of the mechanical virbration patterns of the basila membrane using both the Mossbauer technique and laser interferometry; 2) anatomical and electrical recording studies on the organ of Corti of the mouse in tissue-culture; 3) recordings from single auditory-nerve fibers responding to complex acoustic stimuli, incuding vowel approximations; 4) mathematical modeling of the peripheral auditory system; 5) recordings from single neurons in the cochlear nuclear complex in cat to assess both cochlear output and the transformations imposed by neurons in the complex on information received from auditory-nerve fibers; 6) combined anatomical and electrophysiological studies on the functional organization of auditory cortex. Multidisciplinary methods are used, including microelectrode stimulating and recording techniques with special emphasis on the study of the coding of auditory stimulus information in the temporal discharge patterns of single neurons. Computers are used extensively in controlling the parameters of auditory stimuli, in the collection and analysis of anatomical and physiological data, and in mathematical modeling. Histological identification of recording sites and cytoarchitectonic studies are performed; anatomical techniques include the horseradish peroxidase method, autoradiography, quantitative single cell measurements, and electron microscopy.